From Brooklyn in the Midwood area:

Drive East on Ave N, M...I until you hit Flatlands Ave.
Left on Flatlands
Right on Rockaway Parkway (E 97th Street)
Left on Ave N
Right on E 98th Street
Parking lot on left towards the end of the block.

From Brooklyn near the Belt Parkway:

Take the Belt East to Exit 13 Rockaway Ave Exit
Drive on Rockaway Ave two blocks to Seaview Ave
Right on Seaview Ave
Left on E 98 Street
Parking lot on right towards the begining of the block.

From Queens:

Take the Belt West to Exit 13 Rockaway Ave Exit
Drive on Rockaway Ave two blocks to Seaview Ave
Right on Seaview Ave
Left on E 98 Street
Parking lot on right towards the begining of the block.

By Subway:

Take the L train until the very last stop "Rockaway Pkwy"
Wait for the B42 bus within the train station near the tracks
Get off the bus at Seaview Ave
Cross Seaview by foot walk for a block until E 98
Left on E 98 Street
Parking lot on right towards the begining of the block.
Keep the number of the place handy 718-251-1900 (in case you get lost).